docs: def rotated(self, rotation_center, angle):
          """Returns a RotatedBox that is obtained by rotating this box around a given center by a given angle.
  
          >>> assert RotatedBox([2, 2], 2, 1, 0.1).rotated([1, 1], np.pi/2).approx_equal([0, 2], 2, 1, np.pi/2+0.1)
          """
          rot = np.array([[np.cos(angle), np.sin(angle)], [-np.sin(angle), np.cos(angle)]])
          t = np.asfarray(rotation_center)
          new_c = np.dot(rot.T, (self.center - t)) + t
          return RotatedBox(new_c, self.width, self.height, (self.angle+angle) % (np.pi*2))